Current factor VIII (FVIII) products display a half-life (t1/2) of ∼ 8-12 hours, requiring frequent intravenous injections for prophylaxis and treatment of patients with hemophilia A. rFVIIIFc is a ...recombinant fusion protein composed of a single molecule of FVIII covalently linked to the Fc domain of human IgG1 to extend circulating rFVIII t1/2. This first-in-human study in previously treated subjects with severe hemophilia A investigated safety and pharmacokinetics of rFVIIIFc. Sixteen subjects received a single dose of rFVIII at 25 or 65 IU/kg followed by an equal dose of rFVIIIFc. Most adverse events were unrelated to study drug. None of the study subjects developed anti-rFVIIIFc antibodies or inhibitors. Across dose levels, compared with rFVIII, rFVIIIFc showed 1.54- to 1.70-fold longer elimination t1/2, 1.49- to 1.56-fold lower clearance, and 1.48- to 1.56-fold higher total systemic exposure. rFVIII and rFVIIIFc had comparable dose-dependent peak plasma concentrations and recoveries. Time to 1% FVIII activity above baseline was ∼ 1.53- to 1.68-fold longer than rFVIII across dose levels. Each subject showed prolonged exposure to rFVIIIFc relative to rFVIII. Thus, rFVIIIFc may offer a viable therapeutic approach to achieve prolonged hemostatic protection and less frequent dosing in patients with hemophilia A. This trial was registered at www.clinicaltrials.gov as NCT01027377.
Brown adipose tissue (BAT) is rich in mitochondria and plays important roles in energy expenditure, thermogenesis, and glucose homeostasis. We find that levels of mitochondrial protein succinylation ...and malonylation are high in BAT and subject to physiological and genetic regulation. BAT-specific deletion of Sirt5, a mitochondrial desuccinylase and demalonylase, results in dramatic increases in global protein succinylation and malonylation. Mass spectrometry-based quantification of succinylation reveals that Sirt5 regulates the key thermogenic protein in BAT, UCP1. Mutation of the two succinylated lysines in UCP1 to acyl-mimetic glutamine and glutamic acid significantly decreases its stability and activity. The reduced function of UCP1 and other proteins in Sirt5KO BAT results in impaired mitochondria respiration, defective mitophagy, and metabolic inflexibility. Thus, succinylation of UCP1 and other mitochondrial proteins plays an important role in BAT and in regulation of energy homeostasis.
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•Sirt5 regulates mitochondrial protein succinylation and malonylation in brown fat•Increased succinylation of UCP1 reduces its stability and function•Sirt5KO in BAT leads to metabolic inflexibility and impairs mitochondrial homeostasis•These processes are altered by cold exposure and diet
Wang et al. performed succinyl-proteomics in brown fat (BAT) of normal and Sirt5 KO mice and identified UCP1 as a new target of Sirt5 desuccinylation. UCP1 with succinyl-mimetic mutations displayed reduced activity and stability. Elevated succinylation of mitochondrial protein in Sirt5 KO BAT resulted in altered metabolic flexibility and mitophagy.
Insulin receptors (IRs) on endothelial cells may have a role in the regulation of transport of circulating insulin to its target tissues; however, how this impacts on insulin action in vivo is ...unclear. Using mice with endothelial-specific inactivation of the IR gene (EndoIRKO), we find that in response to systemic insulin stimulation, loss of endothelial IRs caused delayed onset of insulin signaling in skeletal muscle, brown fat, hypothalamus, hippocampus, and prefrontal cortex but not in liver or olfactory bulb. At the level of the brain, the delay of insulin signaling was associated with decreased levels of hypothalamic proopiomelanocortin, leading to increased food intake and obesity accompanied with hyperinsulinemia and hyperleptinemia. The loss of endothelial IRs also resulted in a delay in the acute hypoglycemic effect of systemic insulin administration and impaired glucose tolerance. In high-fat diet-treated mice, knockout of the endothelial IRs accelerated development of systemic insulin resistance but not food intake and obesity. Thus, IRs on endothelial cells have an important role in transendothelial insulin delivery in vivo which differentially regulates the kinetics of insulin signaling and insulin action in peripheral target tissues and different brain regions. Loss of this function predisposes animals to systemic insulin resistance, overeating, and obesity.
Skeletal muscle insulin resistance is a prominent early feature in the pathogenesis of type 2 diabetes. In attempt to overcome this defect, we generated mice overexpressing insulin receptors (IR) ...specifically in skeletal muscle (IRMOE). On normal chow, IRMOE mice have body weight similar to that of controls but an increase in lean mass and glycolytic muscle fibers and reduced fat mass. IRMOE mice also show higher basal phosphorylation of IR, IRS-1, and Akt in muscle and improved glucose tolerance compared with controls. When challenged with high-fat diet (HFD), IRMOE mice are protected from diet-induced obesity. This is associated with reduced inflammation in fat and liver, improved glucose tolerance, and improved systemic insulin sensitivity. Surprisingly, however, in both chow and HFD-fed mice, insulin-stimulated Akt phosphorylation is significantly reduced in muscle of IRMOE mice, indicating postreceptor insulin resistance. RNA sequencing reveals downregulation of several postreceptor signaling proteins that contribute to this resistance. Thus, enhancing early insulin signaling in muscle by overexpression of the IR protects mice from diet-induced obesity and its effects on glucose metabolism. However, chronic overstimulation of this pathway leads to postreceptor desensitization, indicating the critical balance between normal signaling and hyperstimulation of the insulin signaling pathway.
Skeletal muscle insulin resistance, decreased phosphatidylinositol 3-kinase (PI3K) activation and altered mitochondrial function are hallmarks of type 2 diabetes. To determine the relationship ...between these abnormalities, we created mice with muscle-specific knockout of the p110α or p110β catalytic subunits of PI3K. We find that mice with muscle-specific knockout of p110α, but not p110β, display impaired insulin signaling and reduced muscle size due to enhanced proteasomal and autophagic activity. Despite insulin resistance and muscle atrophy, M-p110αKO mice show decreased serum myostatin, increased mitochondrial mass, increased mitochondrial fusion, and increased PGC1α expression, especially PCG1α2 and PCG1α3. This leads to enhanced mitochondrial oxidative capacity, increased muscle NADH content, and higher muscle free radical release measured in vivo using pMitoTimer reporter. Thus, p110α is the dominant catalytic isoform of PI3K in muscle in control of insulin sensitivity and muscle mass, and has a unique role in mitochondrial homeostasis in skeletal muscle.
Summary
Background
MD‐7246, a delayed‐release formulation of linaclotide, is designed to target the ileocaecal junction and caecum with the aim of relieving abdominal pain independently of bowel ...function.
Aims
To evaluate the efficacy, safety and dose–response of MD‐7246 in patients with irritable bowel syndrome with diarrhoea (IBS‐D).
Methods
A randomised, double‐blind, phase 2 clinical trial enrolled adult patients with IBS‐D (Rome IV criteria). Patients were randomised to placebo or once‐daily oral MD‐7246 300, 600 or 1200 μg for 12 weeks. Abdominal and bowel symptoms were assessed daily. Key efficacy endpoints were change from baseline in abdominal pain and responder rates for a 30% reduction in abdominal pain in 6/12 weeks. Additional abdominal pain responder and exploratory bowel function endpoints were also assessed.
Results
Among the 388 randomised patients, there was no significant difference in mean change from baseline in abdominal pain between the MD‐7246 300 μg, 600 μg and 1200 μg groups and placebo (−1.93, −1.58, −1.95 and − 2.01, respectively; p > 0.05 for each group vs placebo). The abdominal pain responder rates in the MD‐7246 groups were similar to or lower than those in the placebo group. All doses of MD‐7246 had a minimal effect on bowel function and were generally well tolerated.
Conclusions
MD‐7246 at the doses studied did not improve abdominal pain relative to placebo in an IBS‐D patient population. Similarly, most additional efficacy endpoints showed no improvement with MD‐7246 relative to placebo.
When tested at 300 μg, 600 μg and 1200 μg, MD‐7246, a delayed‐release formulation of linaclotide, had no significant impact on mean change from baseline in abdominal pain in patients with IBS‐D, relative to placebo over a 12‐week treatment period.
The coronavirus disease 2019 (COVID-19) pandemic has disproportionately impacted Black, indigenous, and people of color (BIPOC). Equitable access to therapeutics is key to addressing health ...disparities. We established a monoclonal infusion program in the emergency department of a safety-net hospital. Our program successfully reached underserved BIPOC communities and was sustained throughout the pandemic.
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